The Arecibo Message - First Human Hello To The Stars

'The Arecibo message' is the first human 'hello' message sent to the stars. The message was beamed via radio waves into space at a ceremony to mark the remodeling of the Arecibo radio telescope on 16 November 1974. We are suppose to receive an extraterrestrial response in about 50,000 years (25,000 each way).